Charge forming and fuel feeding apparatus for internal combustion engines



Jan. 14, 1964 B. c. PHILLIPS CHARGE FORMING AND FUEL FEEDING APPARATUSFOR INTERNAL COMBUSTION ENGINES 7 Sheets-Sheet 1 INVENTOR: BERNARD C.PHILLIPS.

Filed May 2. 1960 BY A NM/1g 0. W

AI,TY.

Jan. 14, 1964 B. c. PHILLIPS 3,

CHARGE FORMING AND FUEL FEEDING APPARATUS FOR INTERNAL COMBUSTIONENGINES Filed May 2, 1960 7 Sheets-Sheet 2 INV EN TOR. BERNARD Z7.PHILLIP 5.

BY I )Janfig .ZIT T Jan. 14, 1964 s. c. PHILLIPS 3,118,009

CHARGE FORMING AND FUEL FEEDING APPARATUS FOR INTERNAL COMBUSTIONENGINES 7 Sheets-Sheet 3 Filed May 2, 1960 IN V EN TOR. BERNARD LT.PHILLIPS.

jl v v q iwmyu ATTY.

1954 B. c. PHILLIPS 3,118,009

CHARGE FORMING AND FUEL FEEDING APPARATUS FOR INTERNAL COMBUSTIONENGINES Filed May 2, 1960 7 Sheets-Sheet 4 INVENTOR: BERNARD L7.FHILLZFE.

Jan. 14, 1964 B. c. PHILLIPS 3, CHARGE FORMING AND FUEL FEEDINGAPPARATUS FOR INTERNAL COMBUSTION ENGINES Filed May 2, 1960 7Sheets-Sheet 5 m2 FIE -214- ZoaZ TIE-Z5- INVENTOR. BERNARD L. PHILLIPS.

AT TY.

1 1964 I I B. c. PHILLIPS 73,118,009

CHARGE FORMING AND FUEL FEEDING APPARATUS FOR INTERNAL COMBUSTIONENGINES '7 Sheets-Sheet. 6

Filed May 2, 1960 m-za- INVENTOR Z BERNARD E. PHILLIPS.

ATTORNEY a 1964 B. c. PHILLIPS CHARGEFORMING AND FUEL FEEDING APPARATUS7 FOR INTERNAL COMBUSTION ENGINES Filed May 2, 1960 7 Sheets-Sheet 7Illlllll INVENTOR Z BERNARD L". PHILLIPS.

a ATTORNEY Unite States Patent CHARGE FORMING AND FUEL FEEDDIG APPA-RATUS FOR INTERNAL COMBUSTION ENGINES Bernard C. Phillips, Toledo, Ohio,assignor to The Tillotson Manufacturing Company, Toledo, Ohio, acorporation of Ohio Filed May 2, 1960, Ser. No. 26,150 8 Claims. (Cl.26135) This invention relates to charge forming and fuel feedingapparatus or arrangement for supplying fuel and air mixture to aninternal combustion engine and more particularly to a charge formingapparatus embodying a flexible diaphragm influenced or controlled byaspiration or reduced pressure in a mixing passage of the apparatus forautomatically regulating the delivery of fuel from a sup ply into themixing passage in accordance with the requirements of the engine.

Charge forming devices or carburetors of the diaphragm type have beenemployed with internal combustion engines and especially where an engineis adapted to be operated in tilted or angular positions as thediaphragm is not appreciably affected by gravity and therefore affordsmore sensitive control of delivery of fuel into a mixing passage.

Charge forming apparatus or carburetors of the diaphragm type which havebeen commercially satisfactory have employed a lever or motionmultiplying means arranged between the diaphragm and a fuel inlet valveof the charge forming apparatus whereby flexure of the diaphragm underthe influence of aspiration or reduced pressure in the mixing passage istransmitted through the motion multiplying means or lever to the fuelinlet valve, the latter regulating the flow of fuel into a diaphragmchamber for delivery into the mixing passage. An example of a carburetorof this character is disclosed in my Patent 2,841,372, granted July 1,1958.

The present invention embraces a carburetor or charge forming apparatusof the diaphragm type wherein the diaphragm movement is transmitteddirectly to a fuel inlet control valve without any intermediate ormotion multiplying means and is adapted for use with a fuel supply orfuel head of comparatively low pressure.

Another object of the invention is the provision of a charge formingapparatus embodying a diaphragm actuated fuel flow control means whereinthe diaphragm is responsive to minute variations in pressure in themixing passage whereby the proper rate of fuel delivery into the mixingpassage is attained to provide a satisfactory combustible mixturedelivered to the engine at all engine speeds.

Another object of the invention is the provision of a charge formingapparatus or carburetor of the diaphragm type wherein the diaphragm isarranged to control a fuel inlet valve without intermediate motionmultiplying or lever means, the carburetor being formed with fueldelivery channels opening into the mixing passage for engine idling, lowspeed and high speed engine operation whereby the high speed fueldelivery system embodies a restricted zone or zones in which the liquidfuel provides a valve means, barrier or capillary seal adapted toprevent air leeding through the high speed fuel delivery system into thelow Speed and engine idling fuel delivery system when the latter systemis in operation.

Another object of the invention is the provision of a charge formingapparatus embodying a diaphragm arranged for direct actuation of a fuelinlet control valve and wherein fuel is delivered into the mixingpassage solely by engine aspiration in a mixing passage, the chargeforming apparatus embodying passages for conveying fuel through a maindelivery system and a secondary fuel delivery system whereby liquid fuelin the main fuel deliv- 3,118,009 Patented Jan. 14, 1964 ICC ery systemestablishes a liquid seal when the engine is operating under idling orlow speed conditions avoiding back bleeding of air through the main fueldelivery system.

Another object of the invention resides in the provision of a diaphragmtype carburetor wherein the metering diaphragm directly influences theposition of a fuel inlet control valve especially adaptable for usewhere a low head of fuel is employed or where the pressure on the fuelat the region of the inlet valve is controlled and maintained at aminimum sufficient to assure closing of the valve when the meteringdiaphragm is flexed away from the valve.

Another object is the provision of a charge forming and fuel feedingapparatus embodying a metering diaphragm arranged for direct actuationof a fuel inlet control valve and a pumping diaphragm arranged to beactuated by a source of varying fluid pressure to establish a lowpressure on the liquid fuel supplied to the region of the inlet valve,the arrangement embodying means for controlling the effectiveness ofvarying fluid pressure on the pumping diaphragm to regulate the pressureon the fuel supplied to the region of the inlet control diaphragm.

Another object of the invention is the provision of a charge formingapparatus embodying a metering diaphragm for liquid fuel arranged to actdirectly on a fuel inlet control valve under the influence of aspirationin a fuel and air mixing passage in conjunction with a multiple Venturiin the mixing passage for amplifying the effectiveness of the aspirationin the mixing passage on the metering diaphragm to provide greatersensitivity of control of fuel delivery into the mixing passage.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, operation and function of the relatedelements of the structure, to various details of construction and tocombinations of parts, elements per se, and to economies of manufactureand numerous other features as will be apparent from a consideration ofthe specification and drawing of a form of the invention, which may bepreferred, in which:

FIGURE 1 is a side elevational view of a carburetor or charge formingapparatus of the invention;

- FIGURE 2 is a top plan view of the carburetor shown in FIGURE 1;

FIGURE 3 is an elevational view of one end of the carburetor shown inFIGURE 1;

FIGURE 4 is an elevational view of the opposite end of the carburetor;

FIGURE 5 is a longitudinal sectional view taken substantially on theline 55 of FIGURE 2;

FIGURE 6 is a transverse sectional view taken on the line 66 of FIGURE2;

FIGURE 7 is a fragmentary detail sectional view taken substantially onthe line 77 of FIGURE 1;

- FIGURE 8 is a detail sectional view taken substan tially on the line88 of FIGURE 1;

FIGURE 9 is a fragmentary enlarged sectional view of a portion of FIGURE6 illustrating a form of fuel inlet valve;

FIGURE 10 is a view similar to FIGURE 9 showing a modified form of inletvalve construction;

FIGURE 11 is a sectional view of a diaphragm illustrating a modifiedform of reinforcement therefor;

FIGURE 12 is an elevational view of a combined charge forming and fuelfeeding apparatus of the invention;

FIGURE 13 is a top plan view of the arrangement shown in FIGURE 12;

FIGURE 14 is an end elevational view of the construction shown in FIGURE12;

FIGURE 15 is a transverse sectional view taken substantially on the line1515 of FIGURE 13;

FIGURE 16 is a transverse sectional View taken substantially on the line1616 of FIGURE 13;

FIGURE 17 is a longitudinal sectional view taken substantially on theline I717 of FIGURE '13;

FIGURE 18 is a sectional view taken substantially on the line 18-18 ofFIGURE 14;

FIGURE 19 is an enlarged fragmentary sectional view of a portion of theconstruction shown in FIGURE 18;

FIGURE 20 is a fragmentary detail sectional view taken substantially onthe line 2020 of FIGURE 14;

FIGURE 21 is a sectional view taken substantially on the line 21-21 ofFIGURE 18;

FIGURE 22 is a longitudinal sectional view illustrating a modified formof mixing passage embodying a multiple Venturi arrangement;

FIGURE 23 is a transverse sectional view through the construction shownin FIGURE 22;

FIGURE 24 is a longitudinal sectional view similar to FIGURE 22illustrating another form of multiple Venturi arrangement in a mixingpassage;

FIGURE 25 is a transverse sectional view through the construction shownin FIGURE 24;

FIGURE 26 is an elevational view of a modified form of charge formingand fuel feeding apparatus of the invention;

FIGURE 27 is a top plan view of the construction illustrated in FIGURE26;

FIGURE 28. is an end elevational view of the arrangement shown in FIGURE26;

FIGURE 29 is a sectional view taken substantially on the line 2929' ofFIGURE 27;

FIGURE 30 is a longitudinal sectional view taken substantially on theline 30'3G' of FIGURE 27;

FIGURE 31 is a sectional view taken substantially on the line 31-31 ofFIGURE 27;

FIGURE 32 is a detail sectional view taken substantially on the line3232 of FIGURE 28;

FIGURE 33 is a fragmentary sectional view taken substantially on theline 3333 of FIGURE 27;

FIGURE 34 is a fragmentary detail sectional view taken substantially onthe line 3434 of FIGURE 27; and

FIGURE 35 is a fragmentary detail sectional view showing a modified formof venting means for the chamber exterior of the metering diaphragm.

While the apparatus of the present invention has particular utility fordelivering a combustible mixture to an internal combustion engine of thetwo cycle type, it is to be understood that the apparatus of theinvention may be employed with four cycle engines. The apparatus of theinvention provides a compact arrangement for delivering fuel and airmixture particularly for low horsepower engines of the characterutilized for powering lawnmowers, chain saws, marine motors or wherevera high tilt tolerance charge forming apparatus is necessary ordesirable.

With particular reference to the arrangement illustrated in FIGURES 1through 9, the apparatus or charge forming device for delivering a fueland air mixture to an engine is inclusive of a body or body memberformed with an air flow or mixing passage 12. The mixing passageincludes an air inlet region 14, a Venturi 16 having a choke band or aregion of maximum restriction 17 and a mixture outlet region 18.

Extending transversely through the air inlet region 14 and journaled insuitable bores formed in the body member 10 is a shaft supporting a disktype valve 22 providing a choke valve or means for restricting air flowthrough the mixing passage particularly for use in starting the enginewith which the charge forming apparatus may be utilized. A portion ofthe shaft 20 extending exteriorly of the member 10 is provided with anarm 24 for manipulating the choke valve 22. The body member 10 isprovided with a bore accommodating an expansive coil spring which biasesa plunger 26 into frictional engagement with the shaft 20 for retainingth C k valve 22 in an adjusted position.

The body or member It is provided with a mounting flange 23 adapted tobe secured to a wall of an engine crankcase 30 of a two cycle type, orwith the intake manifold of an engine of the four cycle type. The flange28 is provided with openings 32 to receive bolts for securing the body10 to a crankcase or a manifold. The inlet region 14 of the body 10 isprovided with a flange 34 having openings to accommodate means forsecuring an air cleaner or air filter (not shown) to the body.

The body member 10 is fashioned with a shallow circular recess 38 whichprovides a liquid fuel receiving chamber. Extending across the recess orchamber 38 is a flexible member, diaphragm or membrane 40 which formsone wall of the chamber 33. An annular gasket 42 is disposed between theperipheral region of the diaphragm and the adjacent portion of the bodymember defining the chamber 38. The diaphragm 4i} and sealing gasket 42are maintained in assembled relation to the body It) by a closure 4-4secured by screws 46 extending into bores formed in the body 10.

The central region of the cover or closure 44 is recessed providing aclearance space or chamber 48 to accommodate flexing movements of thediaphragm 40, the space 48 being vented to the atmosphere through anopening 49. The body 15' may be fonmed of cast metal or molded resinousplastic of a character resistant to the effects of hydrocarbon liquid(fuels. The closure member 44 may be fashioned of sheet metal or ofmolded plastic material. The flexible diaphragm 4G is preferablyfashioned of fabric impregnated with a suitable material such assynthetic rubber to render the diaphragm impervious without impairingthe flexibility thereof The diaphragm is preferably reinforced by meansof a reinforced disk 52 on the inner surface and a circular member ordisk 53 at the opposite surface, these components being maintained inassembled relation by a rivet or member 54 at the central region of thediaphragm. Liquid fuel from the fuel receiving chamber 38 is deliveredinto the restricted zone or choke band 17 of the Ventu-ri 16 through amain or primary orifice, opening or nozzle 55, the same being the exitof a restricted pas sage or channel 56 which is in communicationwith achannel or duct 57.

The orifice and associated channels or ducts provide a primary fueldelivery system for conveying fuel into the mixing passage 12. Thearrangement of the invention embodies a secondary fuel delivery system.As shown in FIGURE 8, the secondary fuel delivery system includes anengine idling orifice 66' provided in'the wall of the mixing passage atthe engine side of the throttle I valve 6 2, and a low speed orifice64-, said orifices 60 and 64 being in communication with a supplementalchamber or bore 65.

The throttle valve 62 is of the disk type and is mounted upon a shaft 66journaled in bores formed in the body member 10, as shown in FIGURE 5. Amanipulab ing arm 67 is mounted upon the shaft 66 for operating thethrottle valve to control the flow of fuel and air mixture into theengine. In the arrangement illustrated in FIGURES 1 through 9, thediaphragm 40 is arranged to directly actuate a fuel inlet valve withoutthe employment of a lever or motion multiplying means for controllingthe flow of liquid fuel from a supply into the fuel receiving chamber38.

As particularly shown in FIGURES 6 and 9, a boss portion 7% of the bodyIt) is bored to receive a tubular fitting 72 which is adapted to beconnected by a flexible tube or hose 74 with a supply of liquidhydrocarbon fuel maintained in a fuel tank positioned above the body ltlwhereby the fuel flows to the fuel inlet passage by gravity. Ashereinafter described, fuel may be delivered to the fuel inlet passagein the carburetor by a fuel feeding or pumping means actuated by varyingfluid pressure.

The fitting 72 is formed with a passage 76 which is in communicationwith a space 77 formed in the body 10. The space or bore 77 is joinedwith a counterbore which is threaded as shown at 78 to accommodate athreaded fitting or valve cage 79. The fitting 79 is formed with aninterior bore 80, the lower end of which is fashioned with an inwardlyextending ledge or flange 81. Seated in the interior of the bore 80 andagainst the ledge or flange 81 is an annular valve seat 82 providing aninlet port for admitting fuel into the diaphragm chamber 38.

Slidably disposed in the. bore 80 is a valve body 84 fashioned with afrusto-conically shaped valve portion 86 terminating in a stem, rodportion or strut 88 adapted to be directly engaged by a head portion 54of the rivet 54 secured to or mounted by the flexible diaphragmconstruction 40.

The body 84 of the inlet valve is preferably of poly onal cross-sectionas, for example, a triangular or square configuration to facilitate thefiow of liquid fuel from the region above the valve along the facets ofthe valve body 84 through the port in the annular valve seat 82 and intothe diaphragm or fuel chamber 38. The upper region of the valve body 84is formed with a recess or bore to accommodate a coil spring 90 adaptedto provide a small biasing force tending to seat the frusto-conicallyshaped valve portion 86 in the valve seat 32.

Reduced pressure set up or established in the fuel chamber 38 byaspiration or reduced pressure in the mixing passage 12 will flex thediaphragm 4t upwardly as viewed in FIGURE 6, which action through thestem 88 moves the valve portion 86 away from its seat 82 facilitatingflow of liquid fuel into the chamber 38 from the supply, the extent ofopening of the valve 86 being dependent upon the extent of upwardflexure of the diaphragm 40 under the influence of reduced pressure inthe mixing passage. The biasing force of the spring tending to close thevalve 86 is very slight, being merely suflicient to prevent vibration ofthe valve body 84 which may ensue by reason of engine vibrations. Theless the amount of biasing force of the spring 90 tending to close thevalve, the more sensitive the diaphragm 40 in the exercise of control offuel flow into the chamber 38.

The seat 82 may be fashioned of synthetic rubber or other materialunaffected by hydrocarbon fuels and the valve body 84, valve portion 86and stem 88 fashioned of aluminum or other lightweight material such asa suitable plastic resin such as Delrin (a polyoxymethylene resin) inorder to provide a high degree of sensitivity for the fuel inlet controlmeans. In certain installations where engine vibration is at a minimumthe biasing spring 90 may be omitted.

The arrangement for feeding liquid fuel from the diaphragm chamber 38 tothe high speed or primary fuel delivery system for the main orifice 55is illustrated in FIGURE 6. The lower end of the duct 57 is closed bymeans of a cap or plug 92. The carburetor body is formed with a boss 94-provided With a bore 96, a portion of the wall defining the bore 96being threaded to accommodate the threaded portion 98 of a needle valvebody 100 which provides a means for regulating or metering delivery offuel to the main orifice 55. The boss 94 is formed with a counterboreaccommodating a sealing annulus 102 which is biased to sealingengagement with the valve body 100 by an expansive coil spring 103disposed between the sealing annulus 102 and a knurled head 184 formedon the valve body or member 100.

The end of the bore 96 is in communication with the duct or passage 57by a channel or passage 106 of comparatively small diameter. The valvemember 100 is provided with a tenon portion 108 which terminates in aneedle valve 110 extending into the small channel or passage 106 asshown in FIGURE 6.

The region of the bore 96 adjacent the tenon 108 on the valve member 100is in communication with the fuel chamber 38 through a passage orchannel 112.

The arrangement for feeding or delivering fuel from the chamber 38 tothe engine idling orifice 60 and low speed'orifice 64 is illustrated inFIGURES 7 and 8. Also formed in the boss portion 94 and spaced from thebore 96 is a second bore 116, a portion of the wall thereof beingthreaded to accommodate the threaded portion 117 of a valve member orbody 118, as shown in FIGURE 7. The boss portion 94 is provided with asecond counterbore adapted to accommodate an annular seal \120 whichsurrounds the valve member 113 and is biased into sealing engagementtherewith by an expansive coil spring 122 disposed between the seal anda knurled head portion 123 formed on the valve body 118. A passage 124opening into the fuel chamber 38 is in communication with the end of thebore 116 by a passage or channel 126 of comparatively small size. Thevalve body 118 is formed with a tenon portion 127 which terminates in atapered valve portion or needle 128 which extends into and cooperateswith the small passage 126 for controlling the flow of fuel to thesecondary orifice system.

The region of the bore 116 adjacent the tenon 127 is connected with thechamber 65 by a passage or channel 13% whereby fuel flowing past theneedle portion 128 into the bore 116 is conveyed by the channel 130 intothe auxiliary chamber 65, fuel being delivered therefrom through thesecondary orifices 60 and 64 dependent upon the position of the throttle62 and the engine speed.

In the operation of the charge forming apparatus illustrated in FIGURES1 through 9, the liquid fuel is delivered into the mixing passage 12,either through the main orifice 55 or the secondary orifices 60 and 64under the influence of reduced pressure or aspiration existent in themixing passage during engine operation. The delivery of fuel into themixing passage is under the infinence of aspiration in the mixingpassage as the fuel chamber 38 is unvented. As the fuel is deliveredinto the mixing passage solely by aspiration or reduced pressure thereinacting upon the diaphragm 40, there is no predetermined or defined fuellevel in the chamber 3 8.

In initiating the operation of the charge forming apparatus orcarburetor illustrated in FIGURES 1 through 9, the choke valve 22 isfirst moved to a closed or substantially closed position and thethrottle valve 62 moved to an open or near open position. The engine isthen cranked, setting up reduced pressure in the mixing passage 12 whichis effective on the main orifice 55 to communicate the reduced pressureto the fuel chamber 38.

Reduction in the pressure in the fuel chamber 33 causes flexure of thediaphragm 4t) upwardly as viewed in FIG- URES 5, 6 and 9, elevating thevalve member 86 through engagement of its strut 88 with the member 55 atthe central region of the diaphragm, moving the valve away from its seat82. The fuel in the supply ducts 76 and '77 flows along the facets ofthe valve body 84 through the port in the annular valve seat 82 into thefuel chamber 38.

The fuel is then conveyed under the influence of reduced pressurethrough the restricted channel 112 past the needle valve 110 into thechannel 57 through the restricted passage 56 and out of the orifice 55into the mixing passage 12. The liquid fuel thus delivered into theVenturi 16 of the mixing passage 12 is there mixed with incoming airadmitted through theinlet 14 of the carburetor to form a combustiblefuel and air mixture which is delivered into the engine crankcase 30.

The high speed fuel adjusting means 110 is regulated by the knurledmember 104 to provide for the amount of fuel required for high speedengine operation. During the period of high speed engine operation withthe throttle 62 in open or near open position, the orifices 60 and 64 ofthe secondary system may or may not deliver additional fuel into themixing passage dependent upon the extent of opening of the throttle 62.

When the throttle 62 is substantially closed in engine idling positionviz. the position shown in FIGURE 8, the engine idling orifice 60 issupplied with fuel from the chamber 38 through the arrangement shown inFIGURE 7. When the throttle 62 is in a partial open position or slightlyaway from idle position, the low speed orifice 64 comes into operationand supplies fuel in addition to the engine idling orifice 60.

The fuel supplied to the supplemental chamber 65 for discharge throughthe secondary orifices 6t) and 64 is conveyed to the supplementalchamber through the following channels viz. the bore 124 shown in FIGURE7 past the needle valve 128 through angularly arranged duct 130 andauxiliary chamber 65 to the secondary orifices. The fuel supplied to thesecondary system, comprising the idle and low speed orifices 6t) and 64,is metered or regulated by adjusting the needle valve 128 bymanipulating the knurled member 123 shown in FIGURE 7.

It is found that during engine operation, a balance is maintainedwhereby the rate of flow of liquid fuel past the inlet valve 86, shownin FIGURES 6 and 9, is substantially equal to the rate of delivery ofthe fuel from the diaphragm chamber 38 into the mixing passage 12through one or more of the orifices or outlets 55, 69 and 64.

It is essential, in order to secure satisfactory operation of the engineat idle and low speeds, to prevent reverse flow of air or air bleedingthrough the main orifice 55 of air from the mixing passage into the fuelto be discharged through the engine idling orifice 60, the low speedorifice 64 or both depending upon the relative position of the throttle62 and the load on the engine.

Ball check valves or other mechanical valve means have been heretoforeutilized to prevent air from the mixing passage bleeding back throughthe secondary fuel system when the idling or low speed filel deliveryarrangement is in operation.

A capillary or liquid seal system utilizing the capillary effect of thefuel in restricted passages or ducts is described in my Patent2,841,372, granted July 1, 1958. The charge forming device or carburetorof the present invention utilizes the principles of the capillary orliquid seal disclosed in this patent. In the embodiment of the inventionillustrated in FIGURES 1 through 9, several zones or regions of fuelrestriction are provided, which together cumulate an effective sealarrangement preventing back bleeding of air through the orifice 55.

With reference to FIGURE 5, the restricted passage 56 providing theoutlet or orifice 55, is of a cross-sectional area to accommodate thepassage of fuel sufiicient to provide a proper fuel mixture at highengine speeds. This region provides a hydraulic seal or capillary sealtending to prevent reverse flow or back bleeding of air into the duct 57shown in FIGURE 6. The annular region surrounding the needle valve 110in the bore or restricted passage 1% also provides a region of capillaryseal.

It is found that the seal strength at the restriction provided by theneedle valve 110 is highly efficient Where the needle or tapered portionof the valve in the bore or restricted passage 1&6 is of a low includedangle and the restricted passage 1G6 made of substantial length.

Thus the needle 110 in adjusted position provides for an annularrestriction of but a few thousands of an inch surrounding the needlewhich, combined with a substantial length of the liquid columnsurrounding the needle, provides a high strength seal in addition tothat provided by the restricted outlet passage 56.

The passage 112 from the diaphragm chamber 38 to the bore 96 surroundingthe tenon portion 168 of valve 110 is also of comparatively smallcross-sectional area, being sufficient to satisfy the maximum mixturerequirements of the engine at high speeds and hence the restriction 112provides a further region of capillary or liquid seal assisting inpreventing back bleeding of air through the orifice 55.

Hence in the arrangement as shown in FIGURE 6, the restricted outletpassage 56, the annular region surrounding the needle valve 110 in therestricted passage 1% and the passage 112 provide three regions ofliquid or capil lary seals wherein the capillary action of the fuel iseffective up to certain pressures to provide valve means effective inpreventing back bleeding of air through the main orifice 55. It is foundby test that the seal strength for carburetors, embodying a Venturihaving a choke band or region up to approximately three-quarters of aninch, is maintained effective under a pressure which will support acolumn of water approximately one inch in height, as pointed out in myPatent 2,841,372.

The seal strength varies approximately inversely to the size of theVenturi and increasing the Venturi size tends to promote a seal oflesser strength.

It is to be noted that for satisfactory operation the capillary sealstrength of the seal regions, when the engine is operating in the lowspeed range, must be greater than the pneumatic force or aspirationrequired to cause flexure of the diaphragm.

It should be noted that the fuel chamber 38 is shallow and is arrangedas close as practicable to the mixing passage 12 to reduce the distancethrough which the fuel must be lifted for discharge into the mixingpassage. When the carburetor is in a so-called normal position, that is,with the mixing passage disposed above the diaphragm 40, the height offuel between the level of the fuel in the chamber 33 and the outletorifice 55 opening into the Venturi functions as a negative head andresists or tends to retard fuel flow through the main orifice or nozzle55 into the mixing passage.

The carburetor or charge forming apparatus illustrated in FIGURES 1through 9 is of the so-called free position carburetor as it isadaptable for operation in extreme angulm and inverted positions. Whenused in an inverted position, in the absence of a fuel pump or means fordelivering fuel under low pressure other than gravity, the fuel tankmust be maintained with the fuel supply level above the carburetor inorder to assure operation. In the capillary seal arrangement, it shouldbe noted that the idle fuel supply is at the inlet side of the highspeed fuel restriction. Such arrangement provides ample supply of fuelto the idle system yet the capillary seal at the main nozzle and thehigh speed adjusting restriction prevents back-bleeding of air throughthe nozzle 55.

The spring 90, biasing the valve 8-6 toward its seat 82, should beproportioned to provide low pressure to normally maintain the valve 86in closed position and prevent the valve from the influence of enginevibrations and avoid uncontrolled flooding of the carburetor. As thefiexure of the diaphragm is controlled by the aspiration or reducedpressure in the mixing passage, it is therefore desirable to maintainthe lowest possible practicable pressure of the spring 90 upon the valve86 in order that the diaphragm be responsive to a minimum of aspirationor reduced pressure rendering the diaphragm sensitive to minutevariations in pressure.

Operation of the charge forming apparatus or carbure tor at a pressurejust slightly below atmospheric pressure in the fuel chamber 33 isessential in order to avoid rupture or breakage of the liquid orcapillary seal in the main fuel delivery system during engine idling orlow speed engine operation. A pressure which will support a column ofwater three sixteenths of an inch in height effective on the diaphragm40 is usually sufficient to overcome the spring 90, the weight of thevalve 86 and the low hydraulic force on the valve 86 to open the valveto admit fuel to the chamber 38.

It is found that the liquid or capillary seal is maintained effective toprevent back bleeding with various sizes of Venturi having a choke bandor restricted region up to a diameter of approximately an inch.

Variation in the strength of the liquid or capillary seal is dependentin a measure upon the sizes of the orifices and fuel passages requiredfor calibration in adapting the charge forming apparatus or carburetorto different engines, temperature conditions and variations in the ratioof the amount of lubricating oil to liquid fuel where oil is added tothe fuel for use in operating engines of the two cycle type.

The strength of the liquid or capillary seal has been found to beconsistent and dependable and may be relied upon as an effective liquidcheck valve to prevent back bleeding of air through the main dischargeorifice into the secondary fuel delivery system when the latter is inoperation. The provision of a shallow chamber 38 reduces to a minimumthe amount of fuel in the diaphragm chamber 38 and hence a minimum ofweight of fuel on the diaphragm, rendering the diaphragm highlysensitive to small variations in pressure in the mixing passage.

FIGURE illustrates a modified form of valve construction for controllingthe admission of fuel into the fuel chamber 38. In this form thediaphragm 4t), valve guide fitting 79' and the inlet connection fitting72' are of the same construction as illustrated in the form ofcarburetor of FIGURES 1 through 9. Seated upon the ledge 81 of thefitting or guide 79 is an annular inlet valve seat 135 which ispreferably fashioned with a central opening of slightly larger diameterthan the opening in the valve seat 82 shown in FIGURE 9.

A valve 137 formed of spherical or ball shape is disposed adjacent thevalve seat 135 in the bore 84' formed in the valve guide 79' and is of adiameter slightly less than the diameter of the bore 84' in order tofacilitate flow of liquid fuel around the ball valve 137. An expansivecoil spring 139 is provided, one end engaging the ball valve 137, theother end seating in a recess 14% formed within the carburetor body 1i).

The spring 139 biases the ball valve 137 toward closed position inengagement with the seat 135. The pressure of the spring being veryslight so that a small reduced pressure in the fuel chamber 38 acting onthe diaphragm is required to control the ball valve 137. The rivetconstruction 142 mounted at the central region of the diaphragm isprovided with an upwardly extending strut or pin 144, the distal end ofwhich is arranged adjacent the ball valve 137 and is adapted, uponupward flexure of the diaphragm 46', to elevate the ball above its seatand open the port in the valve seat 135.

When pressure is increased in the fuel chamber 38, the diaphragm 40' isflexed in the opposite direction, permitting the valve 137 to close theport in the valve seat 135 under the influence of the fuel head andspring bias. In this manner an efficient control is exercised over thefuel flow into the fuel chamber 38 dependent upon the rate of dischargeof the fuel through the main orifice or the engine idling and low speedorifices.

FIGURE 11 is illustrative of a modified form of reinforcement for thediaphragm. The diaphragm 143, shown in FIGURE 11, is reinforced at itscentral region by a circular disk like member 150 which is fashioned ofcomparatively thin sheet material such as aluminum, substantially rigidplastic material such as Delrin, the latter being a resin,polyoxymethylene, which is bonded by a compatible cementitious materialproviding a lightweight reinforcement for the central region of thediaphragm 148.

The diaphragm construction shown in FIGURE 11 may be utilized in theform of construction illustrated in FIG- URES 1 through 9 as the strutor stem 88 on the valve member 86 may directly engage the disk 150during flexure of the diaphragm 148.

FIGURES 12 through 21 illustrate a form of charge forming apparatusembodying fuel feeding means, the charge forming apparatus having a fuelflow control diaphragm acting directly upon a fuel inlet valve, the fuelfeeding means including a diaphragm pumping or pulsing means fordelivering fuel to the charge forming component enabling the positioningof a fuel supply tank below the charge forming apparatus. Thearrangement shown in FIGURES 12 through 21 comprises an association ofcomponents, as in the construction shown in FIG- 1G URES 1 through 9,providing for the capillary or liquid seal in the primary fuel deliverysystem to prevent back bleeding of air into the secondary system whenthe latter is in operation.

The arrangement is inclusive of a carburetor body or body member 16%, ofthe same general shape or contour as the body 10 illustrated in FIGURES1 through 4, formed with a mixing passage 162 which embodies a Venturi163 having a choke band or restricted region 164. The air inlet region165 of the body 160 is provided with a shaft 166 which supports a disktype choke valve 167 for use in starting the engine with which theconstruction is utilized. The mixture outlet region 168 is provided witha throttle shaft 169 to which llS secured a disk type throttle valve 170for controlling the flow of air and fuel mixture to the engine.

The mixture outlet end of the body is provided with a flange 172 adaptedto be secured to the crankcase 173 of a two cycle engine by means ofbolts 1'74. The choke shaft 166 and throttle shaft are providedrespectively with manipulating arms 176 and 177.

The body member 160 is formed with a shallow recess or fuel chamber 38,a flexible diaphragm 40' extending across and forming a flexible wall ofthe fuel chamber 38. A second member or plate 184? is arranged adjacentthe diaphragm 4t) and is formed with a cavity or recess 182 toaccommodate flexing movements of the diaphragm 40'.

As in the form of the invention shown in FIGURES 1 through 9, the chargeforming apparatus shown in FIG- URES 12 through 19 is provided with aprimary fuel delivery system and a secondary delivery system forconveying fuel into the mixing passage to be therein mixed with air toform a combustible mixture.

The primary fuel delivery system includes a fuel discharge outlet ororifice 55 opening into the choke band or zone or restriction 164 of theVenturi 163. The main orifice 55 is in communication with a duct 57 by arestricted passage 56, the end of the duct 57' adjacent the fuel chamber38' being closed by a plug 92.

A boss 94 on the body member 160 is formed with a threaded bore 96 whichreceives a threaded portion 98 of a valve body 104). The boss 94 isfashioned with a counterbore accommodating a sealing ring 102, a coilspring 103' being disposed between the sealing ring and a knurled head104 on the valve body 1%. The bore 96' is in communication with the duct57 by a restricted passage 106', the valve body having a reduced tenonportion 108' terminating in an elongated tapered needle valve 110'extending into and cooperating with the restricted passage 106' toregulate the rate of fuel delivery to the main orifice 55.

The bore 96 is in communication with the fuel chamber 38 by a restrictedpassage 112'. By manually adjusting the valve body 1%, the rate of fueldelivery to the main orifice 55 may be varied by the relative positionof the needle valve 110 in the restricted passage 106'.

The secondary fuel delivery system is inclusive of an engine idlingorifice or outlet passage 18% and a low speed passage or orifice 182shown in FIGURE 17, the passages 180 and 182 being in communication witha duct or supplemental chamber 184 extending substantially parallel withthe axis of the mixing passage. The end of the duct 180 in the mountingflange 172 is closed by a plug 185.

When the throttle valve 170 is in closed position, the low speed orificeor passage 182 is rendered substantially ineffective to deliver fuel asit is at the Venturi side of the throttle valve. As shown in FIGURE 16,the boss portion 94 is formed with a second bore 116 threaded to receivethe threaded portion 117 of a valve body 118', a second counterboreaccommodating a sealing ring 120' and an expansive coil spring 122disposed between the sealing ring and the knurled head 123' on the valvebody 118.

The supplemental chamber 184 is in communication with the bore 116 by arestricted passage 126 into which extends a long tapered needle valveportion 128' formed on a reduced tenon portion of the valve body 118'.The bore 116 is adapted to receive fuel from the chamber 38 through arestricted passage 156. The charge forming arrangement illustrated inFIGURES 12 through 19 en bodies the capillary or liquid fuel seal systemassociated with the high speed fuel delivery arrangement.

The passage 56' terminating in the outlet or orifice 55, the restrictedpassage 112 and the annular region surrounding the tapered needle valve1% provide sealing regions wherein the capillary action of the fuel isefiective to prevent or resist back bleeding of air through the mainorifice 55' into the secondary fuel delivery system comprising orifices18% and 132. The strength of the liquid or capillary seals is effectiveat pressures up to approximately that pressure which will support acolumn of water approximately one inch in height.

The lift factor whereby fuel is aspirated into the mixing passagethrough the orifices at engine idling or low speed positions of thethrottle is below the rupturing pressure of the capillary seal. Incertain installations it may be desirable to provide for a small amountof air bleeding into the fuel in the duct 57 so that an emulsion isasp'rateinto the mixing chamber through the main orifice 55. For thispurpose a restricted air bleed passage 188 may be provided at the airinlet region of the Venturi 163 and the duct or passage 57 as shown inFIGURE 17.

In this form of the invention, fuel flow into the diaphragm or fuelchamber 33 is controlled by a valve arrangement of the same character asillustrated in FIG- URE 9. With particular reference to FIGURE 19, thefuel inlet valve construction is inclusive of a valve guide or fitting79' threaded into a bore formed in the body member 166. The fitting 79is formed with a ledge 81' which positions an annular valve seat member82' within the interior bore 80' in the fitting.

Slidably disposed in the bore 8%) is a valve body 84 having afrusto-conically shaped valve portion 86 which terminates in adownwardly extending strut or pin portion 88' adapted to be engaged bythe head of a rivet or member 54' mounted by the diaphragm 49'. The bodyportion 84 of the valve 85' is of polygonal cross-section providingfacets along which fuel may flow when the valve is moved away from theannular seat 82'. The strut or stem portion 88 of the valve constructionis of lesser diameter than the port in the seat 82' to facilitate fuelflow into the diaphragm chamber 38.

The body portion 84 of the valve is bored to receive a coil spring 90'which exerts a slight bias on the valve member tending to engage thevalve portion 86' with the valve seat to close the port. Reducedpressure transmitted through the fuel delivery orifices and channels romthe mixing passage 162 causes flexure of the diaphragm 4% toward themixing passage and as the diaphragm directly influences the valveportion 86, the latter will be moved away from its seat permitting fuelflow past the valve into the chamber 38 for delivery into the mixingpassage.

The rate of fuel flow into the chamber 39' is dependent upon the mixturerequirements of the engine, and variations in velocity of the airthrough the mixing passage vary the aspiration effective to flex oractuate the diaphragm 4h. The chamber or space 77 at the upper endregion of the fitting 7 9 is supplied with liquid fuel through a channel190 to which fuel is supplied by a fuel feeding arrangement. Secured tothe member 186 is a member 192 which forms a component of a fuel feedingor pumping means.

The member 131 is formed with a recess or cavity 193 and the member 192is formed with a recess or cavity 194. Extending across these cavitiesand between the members 180 and 192 is a second or pumping diaphragm 196formed of flexible impervious material. The mom- 12; her 192 is formedwith a circular recess 198 accommodating a gasket 199.

Fitted into the recess 198 is a cover or closure men ber 2% which seatsagainst the gasket 199 to form a fluid tight joint. The central regionof the member 192 is formed with a boss 291 formed with a threaded boreto receive a bolt 202, the latter extending through an opening in theclosure 2% for securing the closure to the member 192.

An annularly shaped fuel strainer or filter 2114 extends across theannular recess 2125 in the member 192. The recess or cavity at one sideof the pumping diaphragm 196 forms a pumping or pulse chamber 193, thediaphragm nu being adapted to be operated by a source of varying fluidpressure, and where the construction is used with an engine of the twocycle type, the varying pressure in the engine crankcase is utilized asthe varying pressure source.

As particularly shown in FIGURE 20, the member is formed with a channel206 which is in registry with a channel 208 formed in the member let).The channel 2% is in communication with the pumping chamber 193 by meansof a connecting channel 289. A channel 219 in communication with channel293, extends through the mounting flange 172 and is arranged forregistry with a passage or channel 212 formed in the boss portion on thecrankcase provi ing a mating mounting means for the mounting flange 172.

A bushing or member 214 formed with a restriction or passage 215 ofsmall cross-sectional area may be employed in the channel 216 where itis desired to vary the restriction. The size of the restriction 215 inthe member 214 may be varied to modify the effectiveness of the reducedpressure in flexing or setting up a pumping action of the pumpingdiaphragm 196.

The channel 2:18 is in communication with the outlet region 168 of themixing passage by means of a restricted channel or vent passage 216 fora purpose hereinafter explained.

The cavity 194 at the opposite side of the pumping diaphragm 1% providesa fuel receiving compartment, the volume of which is varied by flexureof the pumping dia phragm 196, and is arranged to receive fuel from asupply tank or reservoir (not shown). The member 192 is provided with aninlet port 218, shown in FIGURE 17, and an outlet port 220, shown inFIGURE 18. As shown in FIGURE 21, the pumping diaphragm 196 is formedwith an inlet flap valve portion 222 and an outlet flap valve portion224.

The valve portions 222 and 224 are integrally formed of the material ofthe diaphragm by cutting away U- shaped portions of the diaphragm toprovide the spaces 225 and 226 to facilitate movement of fuel adjacentthe flap valves as they are alternately opened and closed. The valves222 and 224 are adapted to hinge or flex about the linear region oftheir integral juncture with the major area of the diaphragm as shown inFIGURE 21. The inlet valve 222 cooperates with the port 218 in FIGURE 17and the flap valve 224 cooperates with the outlet port 226 shown inFIGURE 18.

The outlet port or passage 220 in member 92 is in communication with thefuel compartment 194 by means of a channel 228. The inlet port orpassage 213 is in communication with the space 205 above the filter 2%through a passage 23%) shown in FIGURE 15, the fuel passing the inletflap valve 222 when the same is open, the fuel flowing through passage232 and 234 into the fuel receiving compartment 194, shown in FIGURES 16and 17.

Formed in member 1819 is a channel 236 which registers with a channel237 formed in the body member 160, the channel 237 being incommunication with the angular channel 199, shown in FIGURES 18 and 19,to facilitate delivery of fuel under the pressure provided by the actionof the pumping diaphragm 196 to the fuel inlet valve arrangement shownin detail in FIGURE 19. The closure 13 member 260 is formed With anelbow shaped portion 24! adapted to accommodate a flexible tube 242adapted to be connected with a fuel tank or other fuel supply.

The elbow shaped portion 240 is provided with a fuel inlet passage 244,shown in FIGURE 15,, to convey fuel from the tubular member 242 into thespace defined by an inner surface of the closure 20%) and through thefilter or strainer 264 into the space 205. When the engine is inoperation, the varying reduced pressure set up in the engine crankcaseis transmitted to the pumping chamber 193 through the connecting orintercommunicating channels 209, 206, 268, 21% restriction 215 andpassage 212, shown in FIGURE 20, so that a pumping action is set up orexerted by the varying pressure upon the pumping diaphragm 196 causingrapid movements or flexure of the diaphragm.

This pumping action or movement of the diaphragm influences flow ofliquid fuel through the fuel receiving compartment 194. During anopening movement of the inlet flap valve 222 when the diaphragm 196 isflexed in one direction, liquid fuel flows from the space 265 throughthe channel 236 and port 218 past the inlet flap valve 222 and throughchannels 232 and 234 into the fuel receiving compartment 194.

When the inlet flap valve is closed and the outlet valve 224 is opened,under the influence of movement of the diaphragm 196 in the oppositedirection, fuel flows through channel 228 and port 22f), shown in FIGURE18, past the outlet valve 224, through the mating channels 236 and 237,thence through channel 198 to the region 77' above the inlet valve 8d,shown in FIGURE 19.

In this manner there is always a supply of fuel under comparatively lowpressure at the region of the fuel inlet control valve 36' so that uponupward flexure of the metering diaphragm 4G, when fuel requirements ofthe engine are increased, the valve 36' is elevated by direct action ofthe diaphragm 4t) and fuel flows past the valve 85 into the diaphragm orfuel chamber 38 thence through either the primary or secondary fueldelivery systems, dependent upon engine speed and load conditions, intothe mixing passage 162 in the manner hereinbefore described.

It is to be understood that the pulsation or pressure variation in theengine crankcase effects a corresponding pulsation or fiexure of thepumping diaphragm 196. The restriction 215 in the pulse line incommunication with the pumping chamber enables a regulation or controlof the pumping effectiveness of the pumping diaphragm 1%. Thus if acomparatively low fuel pressure is desired in the fuel compartment 1%and adjacent the inlet control valve 36, the restriction 215 may be madecomparatively small.

If higher fuel pressure is desired, the restriction may be enlarged tosecure increased pumping flexure or movement of the pumping diaphragmwithin the limits of pressure provided by the crankcase pulsations. Thevent passage 216 shown in FIGURE 20 between the pulse channel 208 andthe outlet region of the mixing passage 168 may be employed asadditional means for reducing or controlling the effectiveness of thepressure pulsations transmitted to the pumping chamber 193. In a twocycle engine, the crankcase usually contains wet fuel and air mixtureand some fuel may enter the pulse channels or passages 210, 203, 236 and2&9.

Through the use of the vent passage 215, wet fuel which may enter thepulse channels is bled into the mixing passage through the vent opening216. The vent opening 216 if increased in size will decrease theeffectiveness of the pulse pressure transmitted to the pumpingdiaphragm. Through the proper correlation of the respective sizes of therestriction 215 and the vent passage 216, the fuel pressure developed bythe pumping diaphragm may be varied or controlled by regulating theeffectiveness of the variable fluid pressures or forces acting upon thepumping diaphragm 196.

It will thus be seen that the fuel feeding and charge formingarrangement illustrated in FIGURES 12 through 20 provides a unitembodying a metering diaphragm arranged for direct action upon the fuelinlet valve in co11- junction with a fuel feeding arrangement in whichthe fuel pressure developed by the fuel feeding arrangement may beeffectively regulated and controlled and wherein the components arecompactly arranged to occupy comparatively small space and whichcomprises a minirnum number of parts.

This form of the invention provides a position free carburetor and fuelfeeding arrangement which is operable in extreme angular positions oftilt and in inverted position as fuel is supplied under pressure to theinlet valve control means irrespective of the relative position of thefuel tank or fuel supply and wherein fuel flow ceases upon stopping theengine with which the arrangement is employed.

The control of the pumping forces acting upon the pumping diaphragm 1%through the utilization of the restricted passage 215 and the ventpassage 216, shown in FIGURE 20 is particularly important in thearrangement wherein the metering diaphragm 4G acts directly upon thefuel inlet control valve 8'. In order to render the metering diaphragm4h sensitive to minute variations in pressure existent in the mixingpassage, the pressure on the fuel above the inlet valve 86 should bekept as low as possible so that the metering diaphragm will beresponsive to minute reduced pressure or low aspiration in the mixingpassage to open the fuel inlet valve 86'.

By proper proportioning of the size of the restriction 215 and ventpassage 216 the effective variable pressure influence the pumpingdiaphragm 196 may be controlled and and thereby maintain the pressure onthe fuel at the inlet valve 86 to a minimum commensurate with practicaloperation of the charge forming apparatus.

FIGURES 22 and 23 illustrate a modified form of charge forming and fuelfeeding apparatus of the general character of the arrangement shown inFIGURES 12 through 21 but incorporating or embodying a multiple Venturiconstnuction in the mixing passage. In this form, the body or bodymember 259 is formed with a mixing passage 251 which includes a main orprimary Ventun' 253 having a choke band or zone of maximum restriction254. The mixing passage includes an air inlet 255 and a mixture outlet256, a choke valve 16711 in the air inlet and a throttle valve 17th: inthe mixture outlet 255.

The secondary fuel delivery system, including an idling orifice 18%, alow speed orifice 132a and associated channels and fuel meteringadjustment are the same as in the form of construction illustrated inFIGURES 12 through 21. The arrangement includes a shallow fuel ordiaphragm chamber 3&1, a metering diaphragm 46a, a member 133a adjacentthe metering diaphragm, a pumping diaphragm a and a member 12a adjacentthe pumping diaphragm, these components being held in assembled relationby screws 1350.

The fuel feed or fuel pumping arrangement illustrated in FIGURES 22 and23 is the same as that illustrated in the form shown in FIGURE 12through 20 and the fuel inlet valve mechanism shown in FIGURE 23 is ofthe same construction as that shown in FIGURE 19. The fuel inlet valveis slidably contained within a valve cage or fitting 790, the stem 88aof the valve adapted to be engaged by the member 54a mounted at thecentral region on the metering diaphragm 40a. A closure member 209a,provided with the fuel entrance elbow 240a, is secured to member 19211by a bolt 202a.

The incoming fuel is filtered or strained through a screen 2640. Thepumping diaphragm 196a is actuated by varying fluid pressure derivedfrom the engine crankcase of a two cycle engine throughintercommunicatin'g channels arranged as shown in FIGURE 20. Positionedcentrally in the Venturi 253 is a supple-mental or second Venturi 258having a choke band or region of maximum restriction 269. In the formshown in FIGURES 22 and 1 .5 23 the primary and secondary Venturis 253and 253 are arranged on a common axis viz the axis of the mix ngpassage.

The outer wall 252' of the supplemental or secondary Venturi is ofcircular shape, as shown in FIGURE 23 and is integrally joined with thebody 254} by a connecting or bridge portion 264. The fuel deliverysystem for high speed operation is substantially the same as that shownin FIGURE 15 except that the main orifice 55:: opens into or dischargesfuel into the choke band 269 of the supplemental or secondary Venturi258. The fuel passage 56a for the orifice 55a opens into a duct 57a.

A high speed adjusting needle valve 1 19a cooperates with a restrictedpassage 19651 to regulate or meter the fuel delivered through the mainorifice 55a. The bore, containing the valve body 9811 provided with theneedle valve 110a, receives fuel from the fuel chamber 3&2 through arestricted passage or channel 112a. The multiple Venturi construction,shown in FIGURES 22 and 23, enables the delivery of a satisfactory fueland air mixture particularly when an engine is operating at low speedsunder comparatively heavy loads.

This advantage is attained by reason of the increase or amplification ofthe aspiration effective on the main nozzle 55a in the supplementalVenturi 258. As the aspiration on the main fuel delivery orifice 55a isappreciably greater for a comparable air flow due to the utilization ofthe supplemental Venturi, the capillary seal regions provided by therestricted passage 56a, the annular region surrounding the needle valve110a and the restricted passage 112a may be proportionately reduced inarea and obtain a satisfactory seal.

Since the annular space surrounding the long slender needle valve l'lilamay be adjusted to a lesser area because of the increased aspiration onthe main fuel orifice 55a, the strength of the capillary seal at thisregion is increased and hence requiring a greater difiercntial inpressure before it is fracture or ruptured.

It is desirable to employ a valve 1152a which is fashioned as a longslender needle of low taper as it provides for a long annular region offuel, providing increased eifectiveness of the capillary action andhence the strength of the liquid seal.

The restricted passages 56a and 112a also have aoumulative effect on theseal strength. These passages should therefore be of a minimumcross-sectional area commensurate with their capacity to convey fuel tothe outlet orifice 55a to satisfy the requirements of the engine at itsmaximum speed.

FIGURES 24 and 25 illustrate a modified form of the carburetor and fuelfeed system shown in FIGURES 22 and 23. In this form the componentscorresponding with like components in FIGURES 22 and 23 are of the sameconstruction with the exception of the charge forming body 230. The body233 is formed with a main or primary Venturi 2535 having a choke band orzone of maximum restriction 254b, the Venturi forming a component of themixing passage 2511:. The mixing passage is provided with a choke valve16715 and a throttle valve 17%.

The carburetor body 280 is formed with a shallow fuel chamber 38b, onewall of which is defined by a metering diaphragm 4% held in place by amember 18%. A pumping diaphragm 1961) is associated with a member 19212,a closure 2%]; provided for the fuel compartment in the member 1921) inthe same manner as shown in FIG- URE 23. The secondary fuel deliverysystem includ ng the secondary orifices 18M) and 18212 and associatedchannels are the same as in the other forms of the invention.

In this form, a supplemental or secondary Venturi 282 is integrallyformed with the body member ass and is disposed in a region of themixing passage 251k at one side of the axis of the mixing passage in theregion nearest the fuel chamber 32%.

As will be apparent in FEGUKES 24 and 25, the axis of the supplem talvcnlguri 2% is offset from the axis of E6 the mixing passage and mainVenturi 253b. The supplemental Venturi 282 is provided with a choke bandor region of restriction 284 and the main fuel discharge orifice 55bopens into the choke band 284 of the supplemental Venturi.

By disposing the supplemental Ventuii as close as practicable to thefuel chamber 381'), that is, in the side of the mixing passage closestto the chamber 38b, less pressure or aspiration is required toeffectively discharge or deliver fuel through the main orifice 551';into the supplemental Venturi. This reduction in the lift factor enablesfuel to be delivered into the supplemental Venturi at appreciably lowerair flow tlno rgh the mixing passage. The fuel conveying passages 56!),11217 and the annular space surrounding the metering needle 1181;provide the capillary seal features in this form as in the other formshereinbefore described.

While there may be some tendency toward Stratification of the fuel inthe mixing passage due to the offset position of the supplementalVenturi 2-82 due to enrichment of the mixture on the lower side orregion of the supplemental Venturi, such condition has no appreciableeffect upon the engine as the air and fuel become thoroughly mixed inthe crankcase of the two cycle eng ne by reason of turbulence thereinand when used with the four cycle engine there is substantial turbulencein the combustion chamber of the engine which promotes uniformdistribution of the fuel in the fuel and air mixture.

The arrangement shown in FIGURES 24 and 25, providing a high lift factorfor delivering fuel from the main orifice into the supplemental Venturi,enables the use of the arrangement in larger capacity carburetorsWithout sacrificing the advantages of the capillary seal for preventingback bleeding of air through the main orifice into the secondary fueldelivery system when one or more orifices of the secondary system are inoperation.

FIGURES 26 through 34 illustrate a modified form of charge forming andfuel feeding apparatus of the invention. In this form, the main orprimary fuel delivery system and the secondary delivery system, the fuelchamber and metering diaphragm acting directly upon a fuel inlet valvemechanism, are substantially the same as the corresponding components ofthe form of the invention illustrated in FIGURES 1 through 9.

This form of the invention includes a body member 309 formed with an airand fuel mixing passage 302-, the mixing passage including a Venturi 3&3having a choke band or region of restriction 3%. The mixing passage isprovided with an air inlet region 386, and a mixture outlet region 367.The outlet end of the body member 309 is provided with a mounting flange308 for connecting the body member with the crankcase of an engine. Theintake region 306 is equipped with a shaft 1660 provided with a chokevalve 1670, the mixture outlet region being provided with a shaft 163 cequipped with a disk-type throttle valve 179C.

The body 3% is formed with a shallow-recess provid ing a fuel chamber35c, a metering diaphragm 49c extending across the recess and forming aflexible wall of the chamber 380. A cover member 319 is provided for themetering diaphragm 46c and the cover member secures the peripheralregion of the diaphragm in contact with the body member 3% by screws312. The central region of the cover member 310 is recessed providing aspace 3 14 to accommodate fiexure of the diaphragm 46c, the space 314being vented to the atmosphere through an opening 315.

The body 3% is formed with a bore adapted to receive a valve guide orfitting 790 in which is slidably mounted a valve body 84c having afrusto-conically shaped valve portion 860 adapted to cooperate with anannular valve seat 820 disposed in a lower portion of the fitting 790 inthe manner illustrated in FIGURE 29, a spring exerting a slight bias onthe valve 860 tending to seat the valve. The end region of the valvemember is provided with a strut or pin 880 which is adapted to heengaged by the 17 member or rivet 54c mounted at the central region ofthe diaphragm 400.

The axis of the valve member 86c is at substantially the central regionof the metering diaphragm 430. The upper end of the bore accommodatingthe valve guide or fitting 79c is in communication with a fuel inletpassage 318. The aspiration or reduced pressure in the mixing passage 3%is communicated through the fuel channels to the chamber 33c, thevariable pressures effecting flexure of the metering diaphragm 460 toinfluence the position of the valve 860 to control fuel flow into thediaphragm chamber 380.

The primary or high speed fuel delivery system includes a main orifice55c opening into the choke band 394 of the Venturi 395, a restricted.passage 56c conveying fuel to the orifice from a fuel duct 570. The bodyis formed with a boss portion 94c which has a threaded boreaccommodating a manually operable valve body 380 formed at its extremitywith a long tapered needle valve portion llfic extending into andcooperating with a restricted passage 1960, the valve body being formedwith a knurled head 1940 for manually adjusting the position of theneedle valve.

A restricted passage 112a conveys fuel from the chamber 38c to theregion of the bore in the boss 94c adjacent the needle valve 1130, thelatter being adjustable to regulate the fuel flow or delivery from themain or primary orifice 550. The restricted passages 56c and 112C andthe annular fuel space surrounding the needle valve 110a providerestricted regions for the formation of capillary seals in the mannerhereinbefore described in reference to the other forms of the inventionto prevent back bleeding of air from the mixing passage through the mainnozzle into the secondary fuel delivery system when the latter is inoperation.

The secondary fuel delivery system, shown in FIGURE 30, includes anengine idling orifice 1800, a low speed orifice 1820 these orificesbeing in communication with a passage or supplemental chamber 1840extending generally parallel with the axis of the mixing passage, theend of the passage being closed by a plug 185C.

As shown in FIGURE 31, the passage 1840 is in communication by means ofa restricted passage 126s into which extends an elongated needle valve1230 formed on the end of a valve body 1184: threaded into a bore formedin the boss portion 94c.

The valve body 1130 is provided with a knurled head portion 123c foradjusting the position of the needle valve 128:: to regulate fuel flowto the secondary orifices 134k: and 1820. The region of the boreadjacent the needle portion 1280 is in communication with the fuelchamber 33c by a fuel duct or passage 186a. As in the other forms of theinvention, the valve member 118a regulates the fuel flow from thechamber 380 to the secondary orifices 180c and 182a.

A restricted air bleed passage 138C may be provided in communicationwith the air inlet region 366 and the fuel duct 570 to bleed air intothe fuel for delivery into the mixing pamage through the main orifice55c. When either or both of the secondary orifices 183a and 182:: aredelivering fuel into the mixing passage, the capillary or liquid sealsprovided in the restricted passages 560, 112C and the annular regionsurrounding the needle valve 106a prevents back bleeding of air from themixing passage through the orifice 55c into the secondary fuel deliverysystem as hereinbefore explained in connection with the form of theinvention shown in FIGURES 1 through 9.

The fuel feeding or pumping means is arranged at a region spaced fromthe metering diaphragm 49c. As shown in the drawings the meteringdiaphragm arrangement, in the normal position of the carburetor body, isat the bottom or beneath the mixing passage and the pumping or fuelfeeding arrangement is disposed above the mixing passage. The bodymember 3% is formed with a boss portion 326 above the mixing passageprovided with a cavity or recess 322 which forms a pumping or pulsechamber. Extending across the cavity 322 is a flexible pumping diaphragm324, a cover plate or member 326 securing the periphery of the diaphragmto the body member 363 by screws 328.

The cover plate 326 is provided with a recess or cavity 330 at theopposite side of the pumping diaphragm 324. The chamber 322 forms apumping or pulse chamber which is in communication with the crankcase ofan engine of the two cycle type, the variable fluid pressure in thecrankcase effecting rapid flexure or reciprocation of the pumpingdiaphragm 324 to effect a pumping action in the fuel chamber 330. Formedin the body 300, as shown in FIGURE 32, is a pulse passage 332 incommunication with the pulse or pumping chamber 322.

The pulse passage 332 extends through the mounting flange 393 andregisters with an opening into the crankcase of a two cycle engine.Mounted in the extremity of the pulse passage 332 adjacent the mountingflange is a member, sleeve or bushing 334 provided with a restriction orrestricted passage 335 for controlling the effective pumping effort ofthe variable fluid pressure upon the pumping diaphragm 324.

A vent opening 336 is in communication with the pulse passage 332 andthe mixture outlet region 397 of the mixing passage and serves to bleedoff any wet fuel or mixture which may enter the pulse passage 332through its communication with the engine crankcase. The vent opening336 also assists in controlling the effective pumping action of thepumping diaphragm 324 supplementing the control provided by therestricted passage 335.

As the metering diaphragm 46c directly acts upon the valve 866, it isdesirable that the pumping pressure developed in the fuel compartment330 be held to a minimum consistent with practical operation in orderthat the upward fiexure of the diaphragm 40c controlling the fuel inletvalve 860 be influenced by comparatively low lift pressure or lowaspiration existent in the mixing passage 332. The member or plate 326is provided with a bore snugly receiving the tenon portion of a nippleor coupling 34! which is adapted to be connected by means of a tube 341with a fuel tank or fuel supply.

The passage 342 in the nipple 340 is in communication with a port 344,shown in FIGURE 30, which is provided with a flap valve 346 formed as anintegral part of the pumping diaphragm 324 and is of the characterillustrated in FIGURE 21. The space 348 shown in FIGURE 30 and formed inthe body 300 providing clearance for movement of the flap valve 346 isconnected by a passage 350 with the fuel compartment 330 whereby fuel isconveyed through the passage in the nipple 340 past the flap valve 346and into the fuel compartment 330.

As shown in FIGURE 34, the fuel compartment 334 is formed with an outletport in communication by means of a passage 352 with an outlet port 345.A flap vaive 356, formed integrally with the pumping diaphragm 324,cooperates with the port 354 to facilitate passage of liquid fuel fromthe fuel compartment 330 through port 354 past the valve 356 and intothe passage 318 adjacent the diaphragm controlled fuel inlet valve 86c.The flap valve 356 is of the configuration illustrated in FIGURE 21.

Thus under the variable fluid pressure impulses transmitted through thepulse passage 332 to the pulse or pump ing chamber 322, the pumpingdiaphragm 324 is rapidly flexed in alternate directions, and through thecooperation of the flap valves 346 and 356, fuel is pumped from thesupply connected with the nipple 346 through the fuel compartment 330into the passage 313 and is admitted into the diaphragm fuel chamber 38cpast the valve 860 under the influence of fiexure of the diaphragmeffected by aspiration or reduced pressures in the mixing passage 3&2.

By varying the area of the restriction 335 and the size of the ventopening 336 an effective control may be exercised over the amplitude ofpumping strokes of the pumping diaphragm 324 and thereby control theamount of fuel pressure set up in the fuel passage 318.

While the metering diaphragm 40c and the pumping diaphragm 324 as shownin FIGURE 29 are disposed at opposite regions of the mixing passage 392and are arranged in substantial parallelism, it is to be understood thatthe position of the pumping diaphragm may be modilied and arranged in aplane at an angle to the plane of the metering diaphragm 40c.

However in practical operation it is found advantageous to position thediaphragms in substantial parallelism to minimize the effect ofvibrations of an engine on the diaphragms as the planes of thediaphragms may be maintained in substantial parallelism with directionsof engine vibrations. It should be noted that the fuel feeding andcharge forming apparatus illustrated in FIGURES 26 through 34 is of thefree position type and is operable in extreme angular or invertedpositions, rendering the construction suitable for chain saws,lawnmowers or in any installation subject to extreme angular positions.

FIGURE 35 illustrates a modified form of venting means for the chamberadjacent the diaphragm cover. In this form the body 35% is provided witha mixing passage 362 including an air inlet passage 3'64 and a Venturi366. The main orifice 55:] opens into the choke band or restrictedregion of the Venturi and receives its fuel from a duct 57d connectedwith the fuel chamber 33:2 in a manner hereinbefore described inreference to the other forms of the invention. The air inlet 364 isprovided with a choke valve 167d mounted upon a shaft 166d. The meteringdiaphragm 40d forming a flexible wall for the chamber 380! is secured tothe body see by a cover plate 363.

The cover plate is provided with a channel 37% registering with achannel 3*?2 formed in the body 366 which is in communication with anangularly arranged tube member 374 opening into the air inlet region364. The passage provided by the channels 37% and 372 and the tubularmember 374 forms a venting means for the chamber see. A venting means orpressure balancing channel of this character may be used where an aircleaner associated with the air inlet 364 may offer appreciableresistance to air flow which may tend to increase the flow of fuelthrough the main orifice 55d.

It is apparent that, within the scope of the invention, modificationsand different arrangements may be made other than as herein disclosed,and the present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

I claim:

1 In combination, a charge forming and fuel feeding apparatus includinga body member formed with a mixing passage, a throttle valve in saidpassage, a fuel chamber in said body member, a first diaphragm forming awall of the fuel chamber, a fuel inlet passage in the body member, afuel inlet valve for said inlet passage, resilient means normallybiasing the fuel inlet valve toward closed position, means mounted bysaid first diaphragm arranged to directly engage and actuate said valveby flexing of the said diaphragm, means establishing pressure on thefuel in the inlet passage including a second diaphragm, a fuelcompartment, a pulsing chamber, said second diaphragm forming a commonwall of said compartment and pulsing chamber, means including a channelconnecting the pulsing chamber with a source of varying fluid pressurefor actuating said second diaphragm, inlet and outlet ports for the fuelcompartment, valve means for said inlet and outlet ports, and ventingmeans for said channel in communication with said mixing passage.

2. In combination, a charge forming and fuel feeding apparatus includinga body member formed with a mixing passage, a throttle valve in saidpassage, 3. fuel chamber in said body member, a first diaphragm forminga wall of the fuel chamber, a fuel inlet passage in the body member, afuel inlet valve for said inlet passage, resilient means normallybiasing the fuel inlet valve toward closed posi tion, means mounted bysaid first diaphragm arranged to directly engage and actuate said valveby flexing of the said diaphragm, means establishing pressure on thefuel in the inlet passage including a second diaphragm, a fuelcompartment, a pulsing chamber, said second diaphragm forming a commonwall of said compartment and pulsing chamber, means including a channelconnecting the pulsing chamber with a source of varying fluid pressurefor actuating said second diaphragm, inlet and outlet ports for the fuelcompartment, valve means for said inlet and outlet ports, a restrictionin said pulsing channel, and venting means for said channel incommunication with the mixing passage.

3. In combination, a body formed with a mixing passa e, a throttle valvein said passage, said mixing passage including a main Venturi, acomparatively small supplemental Venturi in said mixing passage andhaving its axis parallel to and offset from the axis of the mainVenturi, a recess formed in the body, a diaphragm forming with saidrecess a fuel chamber, a main orifice opening into the supplementalVenturi, a fuel inlet passage in said body including a valve chamber;fuel inlet valve means in said chamber including a valve seat, a valve,and means biasing said valve against said valve seat; means mounted onthe center of said diaphragm for direct engagement with said fuel inletvalve means for controlling flow of liquid fuel into the fuel chamber,and channel means arranged to convey fuel from the fuel chamber to themain orifice, the axis of said fuel inlet valve means eing offset withrespect to the bore of said mixing passage, said diaphragm having itscenter coincident with the axis of said fuel inlet valve means andoffset with respect to the bore of said mixing passage, said inlet valvemeans and said diaphragm being positioned closely adjacent said mixingpassage, whereby the offsetting and the positioning of said diaphragmand said valve means closely adjacent to said mixing passage, reducesthe size of the charge forming and fuel feeding apparatus to afford moresensitive control of delivery of fuel into said mixing passage.

4. In combination, a body formed with a mixing passage, a throttle valvein said passage, said mixing passage including a main Venturi, acomparatively small supplemental Venturi in said main Venturi and havingits axis parallel to and offset from the axis of the main Venturi, arecess formed in the body, a diaphragm forming with said recess a fuelchamber, a main orifice opening into the supplemental Venturi, asecondary orifice opening into the mixing passage at a region space fromthe main orifice, a fuel inlet passage in said body including a valvechamber; fuel inlet valve means in said chamber including a valve seat,a valve, and means biasing said valve against said valve seat; meansmounted on said diaphragm for direct engagement with said fuel inletvalve means for controlling flow of liquid fuel into the fuel chamber,and channel means between the orifices and the fuel chamber to conveyfuel from the fuel chamber to the main and secondary orifices, thechannel means between the main orifice and the fuel chamber being formedwith a restricted region for establishing a liquid fuel seal to preventair low from the main passage through the main orifice when thesecondary orifice is delivering fuel into the mixing passage, the axisof said fuel inlet valve means being offset with respect to the bore ofsaid mixing passage, said diaphragm having its center coincident withthe axis of the fuel inlet valve means and offset with respect to thebore of said mixing passage, said inlet valve means and said diaphragmbeing positioned closely adjacent said m xing passage, whereby theoffsetting and positioning of said diaphragm and said valve meansclosely adjacent to said mixing passage reduces the size of the chargeforming and fuel feeding apparatus to afford more sensitive control ofdelivery of fuel into said mixing passage.

5. In combination a charge for .ring and fuel feeding apparatusincluding a body member formed with a mixing passage having a Venturitherein, means for conveying fuel to said mixing passage, a throttlevalve in said passage, said body member having a fuel chamber formedtherein, a first diaphragm forming a Wall of the fuel chamber, a fuelinlet passage in said body member including a fuel chamber; fuel inletvalve means in said chamber including a valve seat, a valve, and meansbiasing said valve against said valve seat; means mounted on said firstdiaphragm for direct engagement with said fuel inlet valve means fortransmitting movements of said first diaphragm to said fuel inlet valvemeans, a comparatively small supplemental Venturi in said mixing passageand having its axis parallel to and offset from the axis of the mainVenturi in a direction toward the fuel chamber, the axis of saidsupplemental Venturi being between the axis of said main Venturi andsaid fuel chamber; means establishing pressure of the fuel in the inletpassage including a second di earn, a fuel compartment, and a pulsingchamber; said second diaphragm forming a common wall of said compartmentand said pulsing chamber, means including a channel connecting saidpulsing chamber with a source of varying fluid pressure for actuatingsaid second diaphragm, inlet and outlet ports for the fuel compartment,fuel valve means for said inlet and outlet ports, the axis of said firstmentioned fuel inlet valve means being offset with respect to the boreof said mixing passage, said first diaphragm having its centercoincident with the axis of said first mentioned fuel inlet valve meansand offset with respect to the bore of said mixing passa c, said firstmentioned fuel inlet valve means and said first diaphragm beingpositioned closely adjacent said mixing passage, whereby the offsettingand positioning of said diaphragm and said valve means closely adjacentto said mixing passage reduces the size of the charge forming and fuelfeeding apparatus to afford more sensitive control of delivery of fuelinto said mixing passage.

6. In combination, a body formed with a mixing passage, a throttle valvein the mixing passage, said mixing passage including main andsupplemental Venturies, said Venturies being located within the cylinderdefined by the bore of said mixing passage, a shallow recess formed insaid body, a fuel metering diaphragm forming with said recess a fuelchamber, a main orifice opening the supplemental Venturi, a secondaryorifice opening into t re mixing passage at a region spaced from thesupplemental Venturi, a fuel inlet passage in said body including avalve chamber, valve means in said valve chamber including a valve seat,a valve, and means biasing said valve against said valve seat; meansmounted on the center of said diaphragm to directly engage and actuatesaid fuel inlet valve means by flexing of said diaphragm; channel meansarranged to convey fuel from the fuel chamber to the main and secondaryorifices, and a restriction between the main orifice and the fuelchamber for establishing a liquid capillary seal to prevent air flowfrom the mixing passage through the main orifice when the secondaryorifree is delivering fuel into the mixing passage, the axis of saidfuel inlet valve means being offset with respect to the bore of said mxing passage, said diaphragm having its center coincident with the axisof said fuel inlet valve means and offset with respect to the bore ofsaid mixing passage, said inlet valve means and said diaphragm beingpositioned closely adjacent said mixing passage, whereby the offsettingand positioning of said diaphragm and said valve means closely adjacentto said mixing passage reduces the size of said charge forming and fuelfeeding apparatus to afford more sensitive control of delivery of fuelinto said mixing passage.

7. In combination, a charge forming and fuel feeding apparatus includinga body member formed with a mixing passage, means for conveying fuel tosaid mixing passage, 21 throttle valve in said passage, a fuel chamberin said 22 body member, a first diaphragm forming the Wall of said fuelchamber, a fuel inlet passage in the body member irl cluding a valvechamber, fuel inlet valve means in said chamber including a valve seat,a valve, and means biasing said valve against said valve seat; meansmounted on the center of said first diaphragm to directly engage andactuate said fuel inlet valve means by flexing of diaphragm; meansestablishing pressureon the fuel In the inlet passage including a seconddiaphragm, afuel con? partment, and a pulsing chamber; said seconddiaphragm forming a common wall of said compartment and pulsing chamber,means including a channel connecting the pulse chamber with a source ofvarying fluid pressure for actuat ing said second diaphragm, inlet andoutlet ports for the fuel compartment, and valve means for said inletand outlet ports, the axis of said first mentioned fuel idler; valvemeans being offset with respect to the bore of said mixing passage, saidfirst diaphragm having its center coincident With the axis of said firstmentioned fuel inlet valve means and offset with respect to the bore ofsaid mixing passage, said first mentioned inlet valve means and saidfirst diaphragm being positioned closely adjacent said mixing passage,whereby the offsetting and position ing of said diaphragm and said firstmentioned valve means reduces the size of said charge forming and fuelfeeding apparatus to afford more sensitive control of de livery of fuelinto said mixing passage. I 1

8. in combination, a charge forming and fuel feedingapparatus includinga body member formed with a nine ing passage, a throttle valve in saidpassage, a fuel sham: her in said body member, a diaphragm forming awall of said fuel chamber, a main orifice opening into said mix=passage, a secondary orifice opening into said mixing passage at aregion spaced from said main orifice, a fuel inlet passage in said bodyincluding a valve chamber; fuel inlet valve means in said chamberincluding a valve seat, a valve, and means biasing said valve againstsaid valve seat; means mounted on said diaphragm arranged for directengagement With said fuel inlet valve meansfor' controlling flow ofliquid fuel into said fuel chamber; channel means between the orificesand the fuel chamber to convey fuel from the fuel chamber to the mainand secondary orifices, said channel means between the main orifice andthe fuel chamber being formed with a restricted region for establishinga liquid fuel seal to prevent all fiow from the min ng passage throughthe main orifice when the secondary orifice is delivering fuel into saidmix ing passage, the axis of said fuel inlet valve means beingoiisetwith respect to the bore of said mixing passage, said diaphragm havingits center coincident with the axis of said fuel inlet valve means andoffset with respect to the bore of said mixing passage, said inlet valvemeans and said diaphragm being positioned closely adjacent said mixingpassage, whereby the offsetting and positioning of said diaphragm andsaid inlet valve means closely adjacent said mixing passage reduces thes ze of said charge forming and fuel feeding apparatus to afford moresensitive control of delivery of fuel into said mixing passage.

References Cited in the file of this patent UNITED STATES PATENTS

1. IN COMBINATION, A CHARGE FORMING AND FUEL FEEDING APPARATUS INCLUDINGA BODY MEMBER FORMED WITH A MIXING PASSAGE, A THROTTLE VALVE IN SAIDPASSAGE, A FUEL CHAMBER IN SAID BODY MEMBER, A FIRST DIAPHRAGM FORMING AWALL OF THE FUEL CHAMBER, A FUEL INLET PASSAGE IN THE BODY MEMBER, AFUEL INLET VALVE FOR SAID INLET PASSAGE, RESILIENT MEANS NORMALLYBIASING THE FUEL INLET VALVE TOWARD CLOSED POSITION, MEANS MOUNTED BYSAID FIRST DIAPHRAGM ARRANGED TO DIRECTLY ENGAGE AND ACTUATE SAID VALVEBY FLEXING OF THE SAID DIAPHRAGM, MEANS ESTABLISHING PRESSURE ON THEFUEL